CN113365758A

CN113365758A - Flow rate control in continuous casting

Info

Publication number: CN113365758A
Application number: CN202080010460.6A
Authority: CN
Inventors: 杨洪良; 马丁·塞登; 尼尔斯·彼得·雅各布森; 安德斯·莱曼
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2019-01-30
Filing date: 2020-01-27
Publication date: 2021-09-07
Anticipated expiration: 2040-01-27
Also published as: EP3883705A1; EP3883705B1; JP7069424B2; KR20210110881A; CN113365758B; JP2022508566A; US20220040755A1; EP3883705C0; WO2020157020A1; KR102319760B1

Abstract

Device (1) for controlling the flow rate in a continuous metal casting crystallizer (2) comprising: at least two first front cores (3) with associated first magnetic coils (4), the first magnetic coils (4) being arranged on one side of the crystallizer; at least two second front cores (5) with associated second magnetic coils (6), the second magnetic coils (6) being arranged on opposite sides of the crystallizer, the at least two second front cores (5) being substantially aligned with the first front cores; an external magnetic circuit (7, 8, 9) connecting the second front core to the first front core to allow a unidirectional magnetic flux to pass through the mold from the first front core to the second front core or from the second front core to the first front core; and a control interface (14) capable of independently controlling the two subsets of first magnetic coils.

Description

Flow rate control in continuous casting

Technical Field

The present disclosure relates to the field of continuous casting of metals, and in particular, to an apparatus for controlling flow rate in a thin slab caster.

Background

Stability control is critical in high speed continuous thin slab casting. The modern, high-productivity thin slab caster has a throughput of up to 8 tons per minute and above. In this case, the inlet flow rate of the molten steel leaving the submerged entry port (SEN) into the crystallizer (mold) is high, resulting in strong turbulence effects and possibly an unstable, fluctuating, time-varying flow pattern in the upper part of the steel strand. Reducing these effects is essential to obtain uniform and constant heat and flow conditions for uniform solidification of the fluid steel in the crystallizer.

In continuous casting machines of today, slab production is often diversified for different grades and sizes. To accommodate these different caster outputs, the operation of the thin slab caster may vary dynamically with width, casting speed, SEN type, SEN immersion, superheat, mold funnel type, etc. One challenging aspect of the process is to provide an equivalent solidification environment independent of caster parameters, with conditions favorable for uniform solidification. In particular in high-speed thin slab casters, there is a risk of excessive meniscus flow velocity, fluctuations, turbulence and drift, which may lead to entrainment of the crystallizer powder or variations in the initial shell solidification.

The electromagnetic brake (EMBR) provides a good alternative to the thin slab caster in a dynamic way to counteract these potential quality degradation phenomena, since it can not only brake the flow of molten steel in the mould, but also adjust this braking force to a suitable level by controlling the current to the brake, according to the inflow speed of the steel.

Conventional deterministic (or open-loop) EMBR controls apply different currents to the EMBR for different continuous casting conditions. Suitable current settings are typically found by tests to assess steel quality and process stability, as well as numerical and physical modeling. In addition to being cumbersome, time consuming and expensive, these methods are suitable for mass production and lack the acuity to handle local and professional events.

EP2633928B1 is an attempted improvement of EMBR control, namely by arranging a plurality of independently controllable magnetic brakes in different regions of the continuous casting mold. This allows the operator some freedom to counteract left/right asymmetry or depth gradients in the molten metal stream. However, by virtue of the arrangement of the magnetic poles, the magnetic brake can only apply a magnetic field in the mold in which at least one local magnetic field is directed opposite to the other local magnetic fields in the mold. In other words, a brake device according to EP2633928B1 having a left and right braking region may operate in modes such as (+, -) mode, (+) mode, but not in e.g. (+) or (+,0) mode.

Disclosure of Invention

One object of the present disclosure is to propose a flow rate control device that allows a more versatile, flexible and/or adaptable flow rate control in a continuous metal casting crystallizer. This object is achieved by the invention as defined by the independent claims.

In a first aspect, there is provided an apparatus for controlling flow rate in a continuous metal casting mold, comprising: at least two first front cores with associated first magnetic coils, the first magnetic coils being arranged on one side of the crystallizer; at least two second front cores with associated second magnetic coils, the second magnetic coils being arranged on opposite sides of the crystallizer, the at least two second front cores being substantially aligned with the first front cores; and an external magnetic circuit connecting the second front core to the first front core to allow a unidirectional magnetic flux to pass through the mold from the first front core to the second front core or from the second front core to the first front core. According to one embodiment, the flow rate control device further comprises a control interface capable of independently controlling the two subsets of first magnetic coils.

The flow rate control means are able to provide unidirectional magnetic fluxes having different strengths in different zones of the crystalliser, since the combination of the external magnetic circuit and the control interface enables some of the first magnetic coils to be controlled independently of other ones of the first magnetic coils. The unidirectional magnetic flux is a magnetic flux directed from the mold side near the first front core toward the mold side near the second front core or a magnetic flux directed from the mold side near the second front core toward the mold side near the first front core unless locally zero. While the presence of an external magnetic loop allows for the generation of a unidirectional magnetic flux, a (+, -) or (-, +) type of magnetic flux may also be applied, where the net flux may be zero (e.g., if the left/right amplitudes are equal) or non-zero (e.g., if the left/right amplitudes are different). The presence of the external magnetic circuit removes the constraint that the direction of at least one local magnetic field in the crystalliser is opposite to the direction of the other local magnetic fields in the crystalliser, as described in EP2633928B 1.

In one embodiment, the control interface enables independent control of two or more subsets of the second magnetic coils. This is in addition to the independent control of two or more subsets of the first magnetic coils allowed by the control interface. The effect of the controllability of the second magnetic coil is that the geometry and/or local strength of the magnetic flux can be controlled more accurately.

The subsets of first magnetic coils and/or the subsets of second magnetic coils may be positioned differently with respect to a transverse direction of the crystallizer. For example, in embodiments where the flow rate control device includes one left and one right first front core and one left and one right second front core, the associated two left magnetic coils may be controllable independently of the associated two right magnetic coils. This may allow for more precise adjustment of the applied magnetic flux with respect to the transverse direction, thereby more precisely controlling the flow rate, including the flow geometry.

In a variant, the flow rate control device may comprise two left and two right first front cores and two left and two right second front cores, wherein the two left first front cores may be arranged at different heights to provide good coverage of the vertical direction of the crystallizer. Similarly, each of the right first front core, the left second front core, and the right second front core may be disposed at different heights. According to this variant, the magnetic coils associated with the two left first front cores are controllable independently of the magnetic coils associated with the two right first front cores. Further, there is also an optional, non-mandatory, control independence (i) between the magnetic coils associated with the upper left first front core and the lower left first front core, (ii) between the magnetic coils associated with the upper left second front core and the lower left second front core, (iii) between the magnetic coils associated with the upper right first front core and the lower right first front core, (iv) between the magnetic coils associated with the upper right second front core and the lower right second front core, and/or (v) between the magnetic coils associated with the two left second front cores and the magnetic coils associated with the two right second front cores.

In the embodiments discussed above, independent control may be achieved by the fact that the control interface includes electrical terminals for energising the magnetic coils of each subset. In other words, electrically separate terminals (or pairs of terminals) are provided for each subset. Alternatively, if the control interface includes a processor and is implemented at least in part in software, the control independence can achieve this effect through software instructions.

In one embodiment, the control interface is adapted to coordinate control of the magnetic coils associated with the aligned pair of front cores. For example, the magnetic coils associated with the left (upper) first front core and the magnetic coils associated with the left (upper) second front core are controlled in a coordinated manner. These cores may be aligned in the sense that their symmetry axes (generally parallel to the transverse direction of the crystallizer) substantially coincide. Coordinated control is to be understood as a substantially equal or proportional control signal or excitation current being applied to both magnet coils such that the resulting magnetic fluxes through both coils are comparable or substantially equal. This may be achieved by providing the control interface with a common electrical terminal (or pair of terminals) for energising ones of those magnetic coils to be controlled in a coordinated manner. Similarly, for a control interface comprising a processor, coordinated control may be achieved by providing corresponding software instructions.

In one embodiment the magnetic coils are controlled based on sensor data related to the temperature profile or temperature gradient in the crystallizer or related to the characteristics of the meniscus. The sensor data may have a spatial resolution with respect to a lateral direction of the mold. That is, the sensor data may include at least one left-side value and one right-side value. In embodiments where the spatial resolution is even finer, there may be three or more different sensor data values corresponding to an equal number of points or areas distributed along the lateral direction of the mold.

In one embodiment, the first and/or second front core is provided with a flux shaping element. This may result in a spatially non-uniform magnetic flux passing through the crystalliser. The flux-shaping element may be reconfigurable.

In one embodiment, the external magnetic circuit comprises a first horizontal core (level core) and a second horizontal core, which can be retracted from the crystallizer to allow crystallizer replacement or maintenance, and an external yoke. This provides a magnetic circuit apt to guide the magnetic field in a substantially closed loop (i.e. from the second front core, through the second horizontal core, the external yoke and the first horizontal core, up to the first front core), the magnetic flux crossing the crystalliser transversely from the first front core and reaching the second front core.

In one embodiment, the flow rate control device is supported such that it can move independently of the crystallizer. Generally, in order to make the casting smoother, the crystallizer is mounted on an oscillating table. The flow rate control device not affected by the oscillation should be mounted on a support structure different from the oscillating table. Since the oscillating table must therefore support a lighter weight, it can have a simpler design, operate more economically, and suffer less wear and fatigue.

In a second aspect, a system for continuous casting of metal is provided, comprising a crystallizer, a supply of molten metal, and a flow rate control device having the above characteristics. Preferably, the system is a thin slab caster.

In general, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. The terms flow rate control device, electromagnetic braking device, electromagnetic brake (EMBR) and short for arrangement are used interchangeably in this disclosure. All references to "a/an/the element, device, component, means, step, etc" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Drawings

Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are partially cut-away perspective views of a thin slab caster with a single magnetic coil on each side of the continuous casting mold;

FIG. 3 is a schematic top view of a thin slab caster including an outer yoke in which the magnet coils on either side of the mold cannot be independently controlled;

fig. 4 is a schematic top view of a thin slab caster comprising left and right magnetic coils independently controllable on each side of the mold and two internal yokes arranged such that the left and right magnetic field directions are opposite to each other.

Fig. 5 is a schematic top view of a thin slab caster including independently controllable left and right magnet coils and an outer yoke on each side of the mold according to one embodiment of the present invention.

FIG. 6 is a front elevational view of a configuration of a flux-shaping member disposed on a forward core of a thin slab caster;

FIG. 7a is a perspective view of a front core of a thin slab caster including a configuration of flux-forming elements;

fig. 7b is a schematic front view of the configuration of the flux-shaping element shown in fig. 7 a;

FIG. 8 is a schematic top view of a thin slab caster including independently controllable left and right magnetic coils and an outer yoke on each side of the mold, where processors, control interfaces and sensors have been indicated, according to one embodiment of the present invention;

FIG. 9 is a perspective view of a continuous casting mold in which there are a plurality of horizontally arranged optical fibers on the walls to sense the temperature distribution inside the mold; and

fig. 10 includes a transverse section (lower portion) of SEN for a thin slab caster and a cross section (upper portion) through line B-B, where velocity distributions v (x) with respect to a transverse direction x and a meniscus height h have been indicated.

Detailed Description

Aspects of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown.

These aspects may, however, be embodied in many different forms and should not be construed as limited; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of all aspects of the invention to those skilled in the art. Throughout the description, like reference numerals refer to like elements, as summarized in the following table of reference numerals.

Fig. 1 and 2 show a thin slab caster system with an electromagnetic braking device of the general type, the cut-away views in fig. 1 and 2 differing in the amount of removal of different opaque objects. In operation, the SEN 13 releases molten metal (such as steel or ferrous or non-ferrous metal alloys) into the crystallizer 2. By the downward force of its own weight and the subsequent weight of the metal added higher up in the crystallizer 2, the metal moves vertically to reach the cooler zone of the crystallizer 2 where it gradually solidifies (crystallizes) and finally leaves the crystallizer 2 as a continuous slab. The crystallizer 2 may be made, for example, of copper, optionally with lubricated or coated internal surfaces to regulate friction, may have a section of about 100mm by 1400mm and is suitable for casting speeds of 5.5 m/min.

The electromagnetic braking device shown in fig. 1 and 2 comprises a first front core 3 (visible only in fig. 2) on the proximal side of the crystallizer 2 and a second front core 5 (visible only in fig. 2) on the distal side of the crystallizer 2. One

magnetic coil

4, 6 surrounds each

front core

3, 5 and is thus associated with said

front core

3, 5. An electrical terminal 10 for energizing at least the magnetic coil 4 on the proximal side is shown. The subdivided proximal end portions 3.1, 5.1 of the first and second

front cores

3, 5 extend through corresponding passages of the cooling medium channels 11.1, 12.1 to the surface of the crystallizer 2, the cooling medium channels 11.1, 12.1 being adapted to remove excess heat. The electromagnetic braking device further comprises a first and a second

horizontal core

8, 9, the first and second

horizontal cores

8, 9 interfacing with the

front cores

3, 5 and further interfacing with the double-sided yoke 7 for closing the magnetic circuit. The interface in the magnetic circuit may be solid or comprise an air gap. The yoke 7 and the

horizontal cores

8, 9 may be of ferromagnetic material such as iron.

The open arrows indicate the direction of the local magnetic flux when the magnet coils 4, 6 are energized. The metal flow in the crystallizer 2 below SEN 13 is exposed to a static magnetic field B substantially perpendicular to the flow velocity v, under the action of the energized

magnetic coils

4, 6. The metal thus experiences braking eddy current forces

F＝σ(E+v×B)×B，

It is essentially the opposite of v, where E is the local electric field and σ is the appropriate unit of conductivity. The electromagnetic braking devices shown in fig. 1 and 2 may not allow to independently control the flow at different lateral positions of the crystallizer 2.

Fig. 3 is a schematic plan view of the thin slab caster having an electromagnetic brake device including the outer yoke 7. The present thin slab caster has characteristics similar to those described with reference to fig. 1 and 2. The electromagnetic braking means with which the continuous thin slab casting machine is equipped comprise a single

magnetic coil

4, 6 on each side of the crystallizer 2. The magnetic coil is energized in accordance with the signal shown by the connected control interface 14 to provide a magnetic flux similar to that shown by the solid arrow. Although the control interface 14 may allow independent control of the two

magnetic cores

4, 6, it is not possible to impart different strengths of transverse magnetic fields in the left and right sides of the mold 2.

Fig. 4 is a top view of yet another prior art casting system having an electromagnetic braking device with left and right first

front cores

3a, 3b associated with left and right first

magnetic coils

4a, 4b and left and right second

front cores

5a, 5b associated with left and right second

magnetic coils

6a, 6 b. The magnetic flux is allowed to circulate by means of the first inner yoke 15 interfacing with the left and right first

front cores

3a, 3b and the second inner yoke 16 interfacing with the left and right second

front cores

5a, 5 b. As in EP2633928B1, the depicted electromagnetic braking device can only generate such magnetic fields with the left-hand and right-hand magnetic fields oriented opposite to one another, since the magnetic flux indicated by the solid arrows is recirculated through the mold 2. This applies regardless of the controllability of the

magnetic coils

4a, 4b, 6a, 6 b.

The present invention proposes a solution for improving the controllability of the magnetic braking field. Fig. 5 is a schematic top view of a thin slab caster having a flow rate control device 1 according to one embodiment of the present invention, the flow rate control device 1 comprising independently controllable left and right magnet coils 4, 6 and an outer yoke 7 on each side of the mold. The left side control interface 14a controls energization of the

magnetic coils

4a, 6a corresponding to the left first and second

front cores

3a, 5 a. Preferably, in the above sense, the two coils are controlled in a coordinated manner. The right control interface 14b is arranged to energise the corresponding coil at the right side of the crystal 2. The flow rate control device 1 allows independent control of the magnetic field through different lateral positions of the crystallizer 2. The magnetic flux can circulate through an external circuit comprising the external yoke 7 instead of through the crystalliser 2. Regarding the general nature of the flow rate control device 1 according to the present invention, reference is made to the above description of the electromagnetic braking device shown in fig. 1-4.

In a variant of the embodiment shown in fig. 5, the first and second

horizontal cores

8, 9 can also be divided into a left first horizontal core, a right first horizontal core, a left second horizontal core and a right second horizontal core. The left first horizontal core will then be joined with the first left paired front core, and so on.

Not explicitly shown in fig. 5 is the support structure of the flow rate control device 1. The flow rate control device 1 is preferably supported to be movable independently of the mold 2. Although the crystalliser 2 may be mounted on an oscillating table, the flow rate control device 1 is preferably mounted on a supporting structure different from the oscillating table. Since the oscillating table can carry lighter loads in this way, its design can be simplified.

Fig. 6 is a schematic view of an arrangement of flux-forming elements arranged on proximal end portions 5.1, 6.1 of

front cores

5, 6 of flow-rate control device 1 in a thin slab caster. The filled squares correspond to the parts extending relatively close to the crystallizer 2, while the empty squares end relatively far from the crystallizer 2. Because the

front cores

5, 6, which may be made of mild steel, iron or other ferromagnetic material, have a much higher permeability than air, the magnetic flux will prefer a shorter air gap and be concentrated there. Thus, the local magnetic field at the short air gap will be relatively stronger than at the long air gap, making the magnetic flux distribution through the crystalliser 2 more flexible. This magnetic flux distribution effect may be even more pronounced if the front core on the opposite side of the crystallizer 2 has symmetrical flux-shaping elements.

The configuration of the flux-shaping element may be adapted to the expected flow pattern in view of the internal geometry of the mould 2, the nature of the SEN 13, the casting speed, etc., so that a suitable braking action is achieved. In some embodiments, the flux-shaping elements may be reconfigured after deployment to become useful in different casting processes or to incorporate later insights about a given casting process. Reconfigurability is ensured if the flux-shaping element is provided as a plurality of freely positionable magnetic protrusions 17 of the type shown in fig. 7 a. The protrusion 17 may be an iron bar or another ferromagnetic material that releasably fits into a recess of each front core. The reconfiguration of the flux-forming elements is preferably performed between successive continuous casting batches.

In the example shown in fig. 6, the flux shaping element will result in a relatively strong magnetic flux in the lower portion, except in the central portion. In another example shown in fig. 7b, the flux-shaping elements are arranged in an approximate bowl shape in a position corresponding to the expected need for a more intense braking on the crystallizer 2. The width of each of fig. 6 and 7b corresponds approximately to the entire width of the mold 2. As shown in the perspective views of fig. 1 and 2, the height may correspond to the upper portion of the mold 2.

Recall that the left and right sides of each configuration shown preferably pertain to respective left and right first (or second) front cores having associated magnetic coils, in accordance with one embodiment of the present invention. This enables dynamic left/right controllability, in addition to the option of reconfiguring the flux-shaping elements between casting batches. In other embodiments with a large number of magnetic coils, the lateral resolution of controllability may be even finer. Although the patterns shown in fig. 6 and 7b are mirror-symmetrical with respect to the left/right direction, an asymmetrical pattern may be used. The asymmetric braking force distribution resulting from such a pattern may be beneficial for stabilizing the asymmetric casting jet from SEN 13.

Fig. 8 is a schematic top view of a thin slab caster comprising independently controllable left and right magnet coils 4a, 4b, 6a, 6b and an outer yoke 7 on each side of the mold 2 according to one embodiment of the present invention. A processor 18, left and

right control interfaces

14a, 14b for energizing the magnetic coils, and left and

right sensors

19a, 19b for detecting various flow parameters are also provided. The flow parameters may comprise a temperature profile or temperature gradient in the crystallizer 2, a meniscus height profile, a meniscus velocity, a meniscus height fluctuation and/or another meniscus characteristic. The

control interfaces

14a, 14b may be connected to or may be implemented as thyristor power converters, such as converters in applicants' DCS series.

The local temperature may be sensed using the method and apparatus disclosed in WO2017032488a1 using a fibre optic device; see in particular fig. 1a, 1b, 1c, 1d and 2 thereof. Fig. 9 of the present disclosure is a perspective view of the upper portion of the continuous casting mold 2 and SEN 13. In the walls of the crystallizer 2 there is a sensor array comprising a plurality of optical fibers (dashed lines) extending horizontally to a transverse aperture, which allow sensing the temperature distribution or the temperature gradient with a high spatial resolution. The resulting sensor data may reveal coagulation anomalies, and may also capture meniscus shape in detail and predict meniscus flow rate. As an alternative to fig. 9, vertically arranged optical fibers may be used. A fully distributed measurement system easily captures flow rates and fluctuations on the left and right sides of SEN 13 and can be easily connected to a left/right independent flow rate control device 1 of the type described above to manage flow asymmetry. High resolution measurement of the temperature in the domain near the meniscus provides sufficient information to independently control the left and right flow rates. One possible alternative control method is based on a separate set of crystallizer level sensors with separate level and fluctuation information from the left and right side.

Fig. 10 shows SEN 13 and the resulting inlet velocity profile v (x). The lower part of the figure is a side cross-section of SEN 13, SEN 13 being embodied as a two-channel fishtail mouthpiece. In the upper drawing of fig. 10, which is a cross section along B-B, it can be seen that SEN 13 has a flat section, which is substantially aligned with the transverse direction of the mold 2. The crystallizer level sensor may allow to track the velocity profile v (x) and the meniscus height h, so that the flow rate control device 1 may be controlled to apply a suitable braking magnetic field to stabilize the flow. The magnetic field may be adapted to have a shape suitable to stabilize the flow of molten metal and to help direct momentum to the meniscus in a twin roll flow mode while minimizing meniscus fluctuations and adjusting the meniscus local flow rate. In one example, for a 100 x 1400mm crystallizer and an inclined inlet velocity condition with a ± 50% velocity variation, the left and right magnitudes of the applied magnetic field must differ by about 23% so that the flow velocities at ± 440mm from the lateral center of the crystallizer 2 are equalized. With the application of this magnetic field, the asymmetry of the meniscus flow is substantially eliminated and the flow velocity peaks are suppressed.

Returning to the description of fig. 8, the inventors have realized that automatic meniscus flow rate and asymmetry control can be established using a combination of a left/right independent flow rate control device 1 and an in-line flow measurement sensor, such as the crystallizer level sensor discussed above. The closed control loop may be implemented in a processor 18, the processor 18 being provided as an industrially suitable computer environment for robust, continuous operation. The control loop may, for example, execute a PID algorithm. As the processor 18, ABB abilitys sold by the applicant may be selected^TMAn optimelt monitor.

When the flow rate of the meniscus in the crystallizer is accurately predicted, the closed-loop control system controls the

control interfaces

14a, 14b of the flow rate control device 1 to apply a varying braking magnetic or electromagnetic field to counter a meniscus speed that is too low or too high. It will be appreciated that the left control interface 14a controls the energisation of both the left first magnetic coil 4a and the left second magnetic coil 6 a; and the right control interface 14b controls the energization of both the right first magnetic coil 4b and the right second magnetic coil 6 b. In the same way, the control loop cooperates with the flow rate control device 1 to mitigate flow pattern asymmetry. For example, a greater flow velocity in one lateral half of the crystallizer 2 can be suppressed by a locally enhanced DC (i.e. non-oscillating) magnetic field. The control may also be controlled for data from electromagnetic level sensors, where high frequency feedback may be used to obtain detailed level and wave information in the probe location. This enables speed control and stability control of the meniscus level in the upper part of the crystallizer 2.

In one embodiment, the control loop includes two parts, the first part being the EMBR current determination based on process inputs such as casting speed, SEN geometry, SEN depth, steel grade, mold size, and similar process characteristics. The determination may depend in part on magnetohydrodynamic simulations and/or recorded empirical data. The second part is the dynamic control of the EMBR. Meniscus level sensors 19 located on the left and right sides of the crystallizer 2 measure meniscus level and meniscus fluctuations, wherein transient values can be taken as inputs to achieve dynamic control of the left and right current of the EMBR. Dynamic control may include a cyclic positive and negative adjustment of the EMBR current value initially obtained based on the process input.

In a further embodiment, the processor 18 connected to the control interface 14 is configured to control the magnetic coils based on numerical simulations of transient flow dynamics in the crystallizer.

Aspects of the present invention have been described above primarily with reference to several embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims.

Reference numerals

Device 1, flow rate control device, and electromagnetic brake device

2 crystallizer

3 first front core

3.1 proximal portion of first front core

4 coil associated with the first front core

5 second front core

5.1 proximal portion of second front core

6 coil associated with the second front core

7 outer yoke

8 first horizontal core

9 second horizontal core

10 electric terminal

11 first cooling medium channel

12 second cooling medium channel

13 submerged entry port

14 control interface

15 first inner yoke

16 second inner yoke

17 magnetic projection

18 processor

19 sensor

Claims

1. Device (1) for controlling the flow rate in a continuous metal casting crystallizer (2), comprising:

at least two first front cores (3) with associated first magnetic coils (4), said first magnetic coils (4) being arranged on one side of the crystallizer;

at least two second front cores (5) with associated second magnetic coils (6), said second magnetic coils (6) being arranged on opposite sides of the crystallizer, said at least two second front cores (5) being substantially aligned with said first front cores; and

an outer magnetic circuit (7, 8, 9) connecting the second front core to the first front core to allow a unidirectional magnetic flux to pass through the crystallizer from the first front core to the second front core or from the second front core to the first front core;

characterized in that the control interface (14) is capable of controlling independently the two subsets of said first magnetic coils.

2. The apparatus of claim 1, wherein the control interface is capable of independently controlling two subsets of the second magnetic coils.

3. The apparatus of claim 1 or 2, wherein the subset of the first or second magnetic coils are positioned differently with respect to a lateral direction of the crystallizer.

4. The apparatus of any preceding claim, wherein each of the subset of the first or second magnetic coils comprises one or more magnetic coils.

5. The apparatus of any one of the preceding claims, wherein the control interface is adapted to coordinate control of the magnetic coils associated with the aligned pairs of front cores.

6. The apparatus of any preceding claim, wherein the control interface comprises electrical terminals (10) for energising the magnetic coils in each subset.

7. The apparatus of any preceding claim, wherein the control interface comprises a processor (18).

8. The apparatus of claim 7, further comprising one or more sensors (19), wherein the processor of the control interface is configured to control the magnetic coil based on sensor data from the sensors, the sensor data representing:

temperature distribution in the crystallizer, and/or

Meniscus height profile, meniscus velocity, meniscus height fluctuation, or other meniscus characteristics.

9. The apparatus of claim 7 or 8, wherein the processor of the control interface is configured to process sensor data with a spatial resolution relative to a lateral direction of the crystallizer.

10. The apparatus of any of claims 7 to 9, wherein the processor of the control interface is configured to control the magnetic coils based on numerical simulations of transient flow dynamics in the crystallizer.

11. The device according to any of the preceding claims, wherein the front core is provided with flux shaping elements for allowing a spatially non-uniform magnetic flux to pass through the crystallizer.

12. The apparatus of claim 11, wherein the flux-shaping element is reconfigurable.

13. The device of claim 12, wherein the reconfigurable flux-shaping element comprises a plurality of freely positionable magnetic protrusions (17).

14. The apparatus of any of the preceding claims, wherein the external magnetic circuit comprises:

first and second horizontal cores (8, 9) arranged to interface with the first and second front cores, respectively; and

an outer yoke (7).

15. The apparatus of claim 14, wherein the horizontal core is retractable from the crystallizer.

16. The device according to any one of the preceding claims, further comprising a support structure allowing the device to move independently of the crystallizer.

17. The apparatus of claim 16, wherein no part of the apparatus is supported by the oscillating table.

18. A system for continuous casting of metal comprising:

a crystallizer (2);

a metal supply device (13); and

the device of any one of the preceding claims.

19. The system of claim 18, which is a thin slab caster.